Laser diode and method for manufacturing a laser diode

ABSTRACT

In an embodiment a laser diode includes a surface emitting semiconductor laser configured to emit electromagnetic radiation and an optical element arranged downstream of the semiconductor laser in a radiation direction, wherein the optical element includes a diffractive structure or a meta-optical structure or a lens structure, wherein the optical element and the semiconductor laser are cohesively connected to each other, and wherein the semiconductor laser and the optical element are integrated with the laser diode.

This is a divisional application of U.S. application Ser. No.16/612,799, entitled “Laser Diode and Method for Manufacturing a LaserDiode,” which was filed on Nov. 12, 2019, which is a national phasefiling under section 371 of PCT/EP2018/064274, filed May 30, 2018, whichclaims the priority of German Patent Application No. 102017112235.4,filed Jun. 2, 2017, all of which are incorporated herein by reference inits entirety.

TECHNICAL FIELD

A laser diode is specified. In addition, a method of manufacturing alaser diode is specified.

SUMMARY OF INVENTION

Embodiments provide a laser diode with an improved radiationcharacteristic. Further embodiments provide a laser diode with aparticularly compact design. Other embodiments provide a laser diodethat is particularly eye safe. Yet other embodiments provide a method ofmanufacturing such a laser diode.

The laser diode, for example, is a semiconductor laser diode which isconfigured to emit electromagnetic radiation during normal operation. Inparticular, the laser diode is configured to emit coherentelectromagnetic radiation of a wavelength range. For example, the powerdensity distribution of the emitted electromagnetic radiation has aGaussian profile transverse to the direction of propagation of theemitted electromagnetic radiation. The electromagnetic radiation is, forexample, electromagnetic radiation in the spectral range from infraredradiation to UV radiation.

According to at least one embodiment, the laser diode comprises asurface emitting semiconductor laser configured to emit electromagneticradiation. The semiconductor laser is, for example, formed by asemiconductor layer stack. In particular, the semiconductor lasercomprises at least one active region configured to generateelectromagnetic radiation during normal operation. Furthermore, thesemiconductor laser may comprise interfaces at which electromagneticradiation generated in the active area is at least partially reflected.For example, the surface-emitting semiconductor laser is configured toemit electromagnetic radiation in the stacking direction of thesemiconductor layers during intended operation. In particular, thesurface-emitting semiconductor laser is a VCSEL. A VCSEL(vertical-cavity surface-emitting laser) is a semiconductor laser inwhich the electromagnetic radiation is emitted transversely orperpendicular to the main plane of the semiconductor chip.

According to at least one embodiment of the laser diode, the laser diodecomprises an optical element which is arranged downstream of thesemiconductor laser in a radiation direction. In intended operation, amajority, at least 50%, in particular at least 90%, or all of theelectromagnetic radiation emitted by the semiconductor laser strikes theoptical element. The optical element is configured to influence theelectromagnetic radiation emitted by the semiconductor laser. Forexample, the optical element is configured to focus or redirect theelectromagnetic radiation emitted by the semiconductor laser or toadjust the radiation profile. In particular, the optical element can beconfigured to divide the electromagnetic radiation emitted by thesemiconductor laser into several partial beams.

According to at least one embodiment, the optical element comprises adiffractive structure. The diffractive structure is configured toinfluence electromagnetic radiation emitted by the semiconductor laser.In particular, the diffractive structure is configured to influenceelectromagnetic radiation by diffraction. For example, the diffractivestructure comprises periodically arranged elements at which theelectromagnetic radiation emitted by the semiconductor laser isdiffracted. The diffractive structure can comprise a plurality of nano-or microscale elements which are periodically arranged along the mainplane of the optical element. In particular, the periodicity and spatialextent of the elements are in the order of the wavelength of theelectromagnetic radiation emitted by the semiconductor laser.

The elements may, for example, be arranged on an outer surface of theoptical element or completely surrounded on all sides by a material ofthe optical element. The elements can, for example, be regions whichhave different refractive indices, different absorption and/or differentreflectivity from those of the materials surrounding the regions. Forexample, the elements of the diffractive structure can each be formed bya recess. In particular, the recesses may be filled with a non-gaseousmaterial.

According to at least one embodiment, the optical element comprises alens structure. The lens structure is configured to influenceelectromagnetic radiation emitted by the semiconductor laser, inparticular by bending, diffraction or refraction. The lens structure maycomprise one lens or one or more rows of lenses. For example, the lensstructure forms a diffusor element.

According to at least one embodiment, the optical element comprises ameta-optical structure. The meta-optical structure is configured toinfluence electromagnetic radiation emitted by the semiconductor laser,in particular by bending, diffraction or refraction. The meta-opticalstructure may comprise substructures that can deflect magnetic and/orelectromagnetic fields. The substructures can be subwavelengthstructures. For example, the substructures have a vertical expansionand/or a lateral expansion in the nanometer range. In particular, themean vertical extent and/or the mean lateral extent of the substructuresare between 100 nm and 1 μm inclusive, between 100 nm and 0.7 μminclusive, between 100 nm and 0.5 μm inclusive, or between 100 nm and0.3 μm inclusive.

In particular, the meta-optical structure may act as a lens. Inparticular, such a lens does not have a classical curved lens shape. Themeta-optical structure is approximately flat, especially planar. Forexample, the meta-optical structure has a maximum roughness, which isdetermined by the vertical expansion of the substructures. Thesubstructures can be arranged closely together. For example, thesubstructures can be columnar. The substructures can be arranged in sucha way that the meta-optical structure as a whole mimics the function ofa lens. In contrast to a classical lens, the meta-optical structure canbe free of bulges and thus ultra-flat.

According to at least one embodiment, the meta-optical structure or thelens structure or the diffractive structure is globally designed as aplanar optical structure. The optical structure, especially the lensstructure, may show local curvatures, for example local convex orconcave curvatures. In particular, the lens structure has one or moreoptical substructures which have local curvatures, wherein the opticalsubstructure or optical substructures preferably are formed as aplanarization layer or are embedded in a planarization layer. Theoptical substructure may comprise one lens or one or more rows oflenses. The optical substructure and the planarization layer may beformed of materials of different refractive indices. The planarizationlayer can be formed as part of the lens structure or as part of theoptical element. The substructures of the meta-optical structure canalso be embedded in a planarization layer.

According to at least one embodiment of the laser diode, the meta-opticstructure or the lens structure or the diffractive structure is embeddedin the optical element. For example, the meta-optical structure or thelens structure or the diffractive structure is surrounded, in particularcompletely surrounded, by a material, such as a material of the opticalelement transmissive for radiation. This material may form anencapsulation layer that partially or completely encloses themeta-optical structure or the lens structure or the diffractivestructure. The material of the encapsulation layer is preferablytransmissive for radiation, in particular transmissive for radiation inthe wavelength range or with respect to the major part of the wavelengthrange of the radiation emitted by the semiconductor laser or the laserdiode. The material may have low absorption in the wavelength range ofthe radiation emitted by the semiconductor laser or laser diode,approximately less than 15%, 10% or less than 5%.

The encapsulation layer may be a planarization layer of the opticalelement. The meta-optical structure or lens structure or diffractivestructure may be fully embedded in the encapsulation layer. Inparticular, the meta-optic structure or lens structure or diffractivestructure does not have an outer surface that is not covered by thematerial of the encapsulation layer. For example, the material and alayer thickness of the encapsulation layer are chosen such that no morethan 30%, 20%, 10%, 5% or 3% of the radiant power of the radiationemitted by the semiconductor laser is absorbed by the encapsulationlayer.

According to at least one embodiment of the laser diode, the opticalelement and the semiconductor laser are cohesively connected to eachother. For example, the optical element and the semiconductor laser arein direct mechanical contact with each other. It is also possible thatthe optical element and the semiconductor laser are connected to eachother by a connection means or intermolecular forces such asVan-der-Waals bonds—for example by direct bonding. All connections inwhich the connecting partners are held together by atomic or molecularforces are referred to as cohesive connections. At the same time, theyare non-detachable connections that can only be separated by destroyingthe connection means and/or the connecting partners.

According to at least one embodiment, the laser diode comprises asurface emitting semiconductor laser, which is configured to emitelectromagnetic radiation, and an optical element which, is arrangeddownstream of the semiconductor laser in a radiation direction, whereinthe optical element comprises a diffractive structure and the opticalelement and the semiconductor laser are cohesively connected to eachother. It is possible that the optical element comprises a meta-opticalstructure or a lens structure instead of the diffractive structure.

A laser diode described here is based, among other things, on thefollowing considerations. In order to adapt the radiationcharacteristics of a laser diode, an optical element can be subordinatedto the laser diode with a diffractive optical structure, a meta-opticalstructure or a lens structure. For example, the optical element can bearranged on a frame or a housing, which surrounds the semiconductorlaser in lateral directions, so that the optical element and thesemiconductor laser are arranged at a distance from each other. Inparticular, the optical element may be configured to influence theelectromagnetic radiation emitted by the semiconductor laser after theelectromagnetic radiation has passed through a region between thesemiconductor laser and the optical element which is filled, forexample, with gas.

The laser diode described here makes use of the idea of connecting theoptical element and the semiconductor laser. A particularly smalldistance between the optical element and the semiconductor laser enablesa particularly compact design of the laser diode. Furthermore, thecohesive connection of the optical element and the semiconductor lasersimplifies the alignment of the optical element relative to thesemiconductor laser. The advantage of this is that the laser diode isparticularly compact. In addition, the laser diode is particularly safesince the risk of tilting or detachment of the optical element isreduced. This makes the laser diode particularly eye safe.

According to at least one embodiment, the optical element is in directcontact with a surface of the surface-emitting semiconductor laserfacing the optical element. For example, the entire surface of theoptical element facing the surface-emitting semiconductor laser is indirect physical contact with a surface of the semiconductor laser. Forexample, the optical element and the semiconductor laser aremechanically connected to each other by means of a bonding process suchas direct bonding. In particular, the semiconductor laser completelycovers the surface of the optical element facing the semiconductorlaser. Advantageously, the direct arrangement of the optical element onthe semiconductor laser enables a particularly compact design of thelaser diode.

According to at least one embodiment of the laser diode, the opticalelement and the semiconductor laser are cohesively connected by aconnection means. For example, the connection means is an adhesive. Inparticular, the connection means is an epoxy resin or silicone. Forexample, the connection means is transparent to the electromagneticradiation generated in the semiconductor laser. For example, theconnection means is arranged over the entire surface of the opticalelement facing the semiconductor laser. Advantageously, the use of aconnection means to connect the optical element and the semiconductorlaser enables a particularly reliable mechanical connection. Thisreduces the risk of detachment of the optical element from thesemiconductor laser.

According to at least one embodiment, the connection means surrounds thesemiconductor laser and the optical element in lateral directions. Forexample, the connection means forms a cladding body in which the opticalelement and the semiconductor laser are at least partially encapsulated,injected or the like. For example, the optical element and thesemiconductor laser are completely surrounded by the connection means inlateral directions. Lateral directions are directions that aretransverse or perpendicular to the radiation direction of thesemiconductor laser. In particular, the semiconductor laser is only freeof the connection means on one side facing away from the opticalelement. Alternatively, the semiconductor laser and the optical elementcan be directly cohesively connected to each other. In this case, theoptical element can only be free of the connection means on a sidefacing away from the semiconductor laser. In particular, the opticalelement is completely surrounded on all sides by the connection means.Advantageously, the surrounding of the semiconductor laser and theoptical element by means of the connection means enables a particularlyrobust design of the laser diode.

According to at least one embodiment of the laser diode, the opticalelement is formed with a material which—within the manufacturingtolerance—has the same refractive index as the connection means. “Withinthe manufacturing tolerance” means that the refractive indices differ byno more than 10%, preferably by no more than 5%, in particular by nomore than 1%. In particular, at an interface between the connectionmeans and the optical element, the electromagnetic radiation emitted bythe semiconductor laser is not refracted or is hardly refracted at all.For example, the connection means has a refractive index ofapproximately 1.5 and the optical element is formed at least at theinterface to the connection means with a material having a refractiveindex of approximately 1.5. Advantageously, an efficiency loss due toreflections at the interface between the connection means and theoptical element is thus reduced.

According to at least one embodiment of the laser diode, thesemiconductor laser and/or the optical element are/is laterally enclosedby a cladding. In plan view, the semiconductor laser and the opticalelement can remain uncovered by the cladding. In particular, thecladding is configured to reflect or absorb the electromagneticradiation emitted during operation of the semiconductor laser. Along thevertical direction, the cladding has a vertical height which is smallerthan the sum of a vertical height of the semiconductor laser and avertical height of the optical element. In particular, the verticalheight of the cladding is less than the sum of the vertical heights ofthe semiconductor laser, the optical element and the portion of theconnection means disposed between the optical element and thesemiconductor laser.

According to at least one embodiment of the laser diode, the cladding isformed from a material which is or acts as a radiation absorber orreflector at least for visible light and/or for light in the infraredspectral range. The cladding can completely enclose the semiconductorlaser and the optical element laterally. In particular, the claddingpartially covers side surfaces of the optical element such that the sidesurfaces of the optical element essentially remain uncovered by thecladding at least from a vertical height or at least from an upper edgeof the diffractive structure or the meta-optical structure or the lensstructure. Below the vertical height or the upper edge up to thesemiconductor laser, the side surfaces of the optical element, theconnection means and/or the semiconductor laser may be completelycovered by the material of the cladding. For example, the claddingcompletely covers the side surfaces of the semiconductor laser. Inparticular, the laser diode is a component with an integratedsemiconductor laser and an integrated optical element.

A vertical height of the diffractive structure or the meta-opticalstructure or the lens structure is in doubt the vertical position of thesubstructures of the diffractive structure, the meta-optical structureor the lens structure. The upper edge of the diffractive structure, themeta-optical structure or the lens structure is in particular a surfaceof the diffractive structure, the meta-optical structure or the lensstructure or their substructures facing away from the semiconductorlaser. The upper edge can be formed by the surfaces of the opticalsubstructure facing away from the semiconductor laser or the opticalsubstructures of the diffractive structure, the meta-optical structureor the lens structure. The upper edge is not necessarily formed by anouter surface of the optical element. Alternatively, the upper edge maybe formed by an outer surface of the optical element facing away fromthe semiconductor laser.

According to at least one embodiment of the laser diode, thesemiconductor laser and the optical element are covered in plan view bya cover layer transmissive for radiation. For example, the cover layeradjoins the cladding, especially directly adjoins the cladding. Inparticular, the cladding completely covers the side surfaces of thesemiconductor laser. The side surfaces of the optical element can be atleast partially or completely covered by the cladding.

The cover layer is preferably made of a material that is radiolucent fora large part of the light emitted by the semiconductor laser. The majorportion of the light emitted by the semiconductor laser is in particularthe radiation portion with a simple standard deviation around the peakwavelength of the light emitted by the semiconductor laser.

For example, the cover layer is made of a material that is transparentto visible light and/or electromagnetic radiation in the infraredspectral range. For example, the cover layer is formed with an epoxymaterial or silicone, preferably a clear-sighted material. However, itis possible that the material is selected in such a way that the coverlayer is radiation-impermeable to visible light and transmissive, inparticular transparent, to electromagnetic radiation in the infraredspectral range. For example, the semiconductor laser is configured suchthat it emits electromagnetic radiation with a peak wavelength in theinfrared spectral range during operation.

According to at least one embodiment of the laser diode, the cladding isformed of a material which is or acts radiation-impermeable, preferablyradiation-absorbing, to a major part of the light emitted by thesemiconductor laser. In this sense, the cladding is in particular madeof a black, especially absorbent material. If the material of thecladding is impermeable to visible light, the cladding can produce ablack color impression for the human eye under normal lightillumination. The cladding is preferably configured to be impermeable toradiation. This can be achieved by selecting the appropriate materialand adjusting the thickness of the cladding.

The radiation-impermeable cladding ensures that the electromagneticradiation emitted by the semiconductor laser does not exit the laserdiode from a side surface before it hits the diffractive structure, themeta-optical structure or the lens structure. The laser diode cantherefore be designed to be particularly eye-safe. The risk of crosstalkcan be reduced or minimized. In addition, an increased contrast isachieved at a radiation exit surface of the laser diode. The peakwavelength of the radiation emitted by the semiconductor laser ispreferably a wavelength in the infrared or visible spectral range.

According to at least one embodiment of the laser diode, the cladding ismade of a radiation-impermeable material. Preferably, the cladding is,in particular with regard to the choice of material and its layerthickness, designed in such a way that the cladding isradiation-impermeable to light in the infrared spectral range. Amaterial and a layer thickness of the cover layer can be selected suchthat the cover layer is radiation-impermeable for light in the visiblespectral range and radiation-permeable for light in the infraredspectral range. For example, the cladding is made of a material that isor acts radiation-impermeable to light in the infrared spectral range,preferably radiation-absorbing. In particular, the cover layer is madeof a material that is or acts radiation-absorbing for light in thevisible spectral range and radiation-transmissive for light in theinfrared spectral range.

According to at least one embodiment of the laser diode, the laser diodecomprises a mask. The mask is formed in a vertical direction between theoptical element and the semiconductor laser. The mask is preferablyconfigured to generate a pictogram. For example, the mask is a shadingmask with regions transmissive for radiation and regions nottransmissive for radiation. In particular, the regions transmissiveand/or not transmissive for radiation form a predetermined patternwhich, for example, represents a predefined pictogram. During operationof the laser diode, the pictogram can be projected onto a targetsurface. The optical element allows the pattern of the mask to beenlarged as a pictogram on the target surface. The pictogram can bereproduced by illuminated or non-illuminated parts of the targetsurface.

According to at least one embodiment of the laser diode, the laser diodecomprises a spacer. The spacer is arranged vertically between theoptical element and the semiconductor laser. The spacer is preferablyconfigured to set a predetermined distance between the mask and thesemiconductor laser. In addition, the spacer may be arranged to set apredetermined distance between the optical element and the semiconductorlaser or between the optical element and the mask. Preferably, thespacer is designed to be transparent to the radiation emitted by thesemiconductor laser. For example, the spacer has a vertical layerthickness, particularly between 50 μm and 1 mm inclusive, approximatelybetween 50 μm and 500 μm inclusive, or between 100 μm and 500 μminclusive.

The mask may be formed on the optical element or on the spacer, inparticular directly. It is possible that the mask is formed as part ofthe optical element or as part of the spacer. In particular, thesemiconductor laser, the spacer, the optical element and/or the mask arecohesively connected to each other.

According to at least one embodiment of the laser diode, a regionbetween the optical element and the semiconductor laser is filled withnon-gaseous material. In particular, no gaseous material is arrangedbetween the semiconductor laser and the optical element. For example,there is no air gap, pore and/or other structure between the opticalelement and the semiconductor laser filled with a gaseous material. Inparticular, there is no nitrogen, ambient air, argon and/or other noblegas between the semiconductor laser and the optical element. Inparticular, only material having a refractive index of at least 1.1,preferably at least 1.3, is arranged between the optical element and thesemiconductor laser. Advantageously, a laser beam emitted by thesemiconductor laser has a smaller beam widening when passing exclusivelythrough materials having a refractive index greater than 1. Thus, theoptical element can advantageously be particularly compact, since only asmall beam widening takes place between the surface of the semiconductorlaser facing the optical element and the optical element.

According to at least one embodiment, the optical element does notcompletely cover the surface of the semiconductor laser facing theoptical element. For example, the optical element only covers that partof the surface facing the optical element through which thesemiconductor laser emits coherent radiation during normal operation. Inparticular, the optical element covers a maximum of 90%, preferably amaximum of 60%, of the area of the semiconductor laser facing theoptical element. In plan view of the laser diode, the optical elementhas in particular a smaller cross-section than the semiconductor laser.In particular, the optical element does not project beyond the surfaceof the semiconductor laser facing the optical element in lateraldirections, parallel to the main extension of the optical element.Advantageously the optical element can be realized in a particularlyspace-saving way, so that a particularly small amount of the material ofthe optical element is required for the production of the opticalelement.

According to at least one embodiment of the laser diode, the opticalelement terminates flush with the semiconductor laser in lateraldirections. Lateral directions run parallel to the main extension planesof the optical element. In particular, the side surfaces of thesemiconductor laser connecting the side facing the optical element andthe side facing away from the optical element are parallel to the sidesurfaces of the optical element connecting the surface facing thesemiconductor laser with the surface facing away from the semiconductorlaser. For example, the side surfaces of the optical element and theside surfaces of the semiconductor laser are produced in a commonprocess step. Advantageously, a flush termination of the semiconductorlaser and the optical element in lateral directions enables aparticularly stable connection between the semiconductor laser and theoptical element, since, for example, the entire surface of thesemiconductor laser facing the optical element is used to produce themechanically fixed connection. In addition, flush termination in thelateral direction of the optical element and the semiconductor laserenables a particularly compact design of the laser diode.

According to at least one embodiment of the laser diode, the diffractivestructure or the meta-optical structure or the lens structure isarranged at a distance from the surface of the semiconductor laserfacing the optical element. For example, a side of the optical elementfacing the semiconductor laser may be formed with a first layer and aside of the optical element facing away from the semiconductor chip maybe formed with a second layer. For example, an interface between thefirst and second layers of the optical element has a structuring withwhich the elements of the diffractive structure are formed. The firstand second layers may each have a main extension plane parallel to themain extension plane of the optical element and/or semiconductor laser.The first and second layers may be formed by materials with differentoptical properties. For example, the optical properties can be differentrefractive indices, different absorption coefficients and/or differentreflectivity. For example, the first layer may comprise recesses filledwith the material of the second layer. In particular, the second layeris formed with several non-contiguous regions which are completelysurrounded by the material of the first layer in lateral directions,especially in all directions.

The diffractive structure or the meta-optical structure or the lensstructure can be arranged on a side of the first layer facing away fromthe semiconductor laser. For example, the first layer has apredetermined thickness, which is greater than 0. In particular, thethickness of the first layer is at least 200 μm. Furthermore, betweenthe diffractive structure and the semiconductor laser, or between thelens structure and the semiconductor laser, or between the meta-opticalstructure and the semiconductor laser, there may be arranged aconnection means which, for example, has a thickness of at least 100 μm,in particular at least 200 μm. The connection means forms in particulara connecting layer. For example, the distance between the diffractivestructure or the meta-optical structure or the lens structure and theside of the semiconductor laser facing the optical element is at least25 μm, in particular at least 250 μm. For example, the diffractivestructure or the meta-optical structure or the lens structure isarranged at a distance from the surface of the semiconductor laserfacing the optical element of at least the thickness of the first layerand/or the connection means. For example, the first layer is made ofglass or a glass-like material.

Furthermore, the diffractive structure or the meta-optical structure orthe lens structure can be arranged on a side of the optical elementfacing the semiconductor laser. For example, the diffractive structureor the meta-optical structure or the lens structure is arranged at adistance from the surface of the semiconductor laser facing the opticalelement of the thickness of the connection means arranged between thesemiconductor laser and the optical element. In particular, thediffractive structure or the meta-optical structure or the lensstructure is arranged at the interface between the optical element andthe connection means. For example, the diffractive structure is formedby structuring the surface of the optical element facing the connectionmeans.

Advantageously, the distance of the diffractive structure or themeta-optical structure or the lens structure to the radiation exitsurface of the semiconductor laser facing the optical element can beadjusted particularly precisely by adapting individual layers of theconnection means and/or the optical element.

According to at least one embodiment of the laser diode, the verticaldistance between the diffractive structure or the meta-optical structureor the lens structure and the connection means or the side of thesemiconductor laser facing the optical element is covered, in particularcompletely covered, by the cladding. The distance may be greater than 50μm, 100 am, 200 μm or greater than 300 μm, for example, between 50 μmand 950 μm inclusive, approximately between 100 μm and 500 μm inclusive.For example, the distance is given by a vertical portion of a base bodyof the optical element, wherein the portion is free of substructures ofthe diffractive structure or the meta-optical structure or the lensstructure. Above the vertical part, i.e., further away from thesemiconductor laser, the substructures of the diffractive structure orthe meta-optical structure or the lens structure can be formed orembedded in the base body. For example, the portion or the base body ofthe optical element is a glass body. It is possible that the entire sidesurfaces of the base body or optical element are covered by the claddingmaterial.

According to at least one embodiment, an anti-reflection layer isarranged exclusively on an outwardly exposed surface of the opticalelement. For example, the optical element is arranged in direct contactwith a surface of the semiconductor laser facing the optical element, orthe optical element is arranged on the semiconductor laser by means of aconnection means, wherein the refractive index of the connection meansdeviates by a maximum of 0.2, preferably by a maximum of 0.1, from therefractive index of the material of the side of the optical elementfacing the semiconductor laser. Advantageously, no additionalantireflection coating is necessary on the side of the optical elementfacing the semiconductor chip, since reflections are avoided at thisinterface of the optical element due to the small difference between therefractive indices of the optical element and the connection means.

According to at least one embodiment, an electrical contact surface isarranged on the surface of the semiconductor laser facing the opticalelement and the contact surface is not covered by the optical element.For example, the optical element does not completely cover the surfaceof the semiconductor laser facing the optical element. Thus, the opticalelement can be arranged directly on the semiconductor laser andstructures of the semiconductor laser which are placed on a side facingthe optical element are not covered by the optical element. For example,the contact surface is configured to electrically contact thesemiconductor laser and supply it with current. The contact surface, forexample, is formed by a metal layer. Advantageously, the optical elementcan also be arranged directly on the radiation exit surface of thesemiconductor laser if the semiconductor laser has functional structureson a side facing the optical element.

According to at least one embodiment, the semiconductor laser compriseselectrical contact surfaces exclusively on a side facing away from theoptical element. For example, all surfaces of the semiconductor laser,with the exception of the surface on which the electrical contactsurfaces are arranged, are completely covered by a connection means.Advantageously, such a design enables a particularly robust and compactlaser diode.

In addition, a method of manufacturing a laser diode is specified. Inparticular, a laser diode described here can be manufactured using thismethod. This means that all features disclosed for the laser diode arealso disclosed for the method and vice versa.

According to at least one embodiment, the method of manufacturing alaser diode comprises a method step A in which a plurality of surfaceemitting semiconductor lasers are provided in a first composite. Forexample, the plurality of surface emitting semiconductor lasers ismanufactured in a common process. In particular, the entire composite ofthe plurality of surface emitting semiconductor lasers is manufacturedin a common process. For example, the plurality of surface emittingsemiconductor lasers in the first composite are arranged on a commoncarrier. In particular, the plurality of semiconductor lasers ismanufactured on the carrier. For example, the plurality of surfaceemitting semiconductor lasers is arranged in a lateral plane side byside. In particular, the plurality of surface-emitting semiconductorlasers is arranged side by side at the nodes of a regular rectangulargrid. For example, the first composite is a wafer composite in which thelaser diodes are manufactured together.

According to at least one embodiment of the method of manufacturing alaser diode, a plurality of optical elements are provided in a secondcomposite in method step B. For example, the plurality of opticalelements is manufactured in a common process. The plurality of opticalelements is, for example, arranged side by side in a lateral plane. Inparticular, the plurality of optical elements is arranged side by sidein a lateral plane at the nodes of a regular rectangular grid.

According to at least one embodiment of the method of manufacturing alaser diode, the plurality of optical elements and the plurality ofsemiconductor lasers are cohesively connected in a method step C. Forexample, the optical elements and the semiconductor lasers are connectedto each other by means of a connection means. Alternatively, the opticalelements and the semiconductor lasers can be bonded together. Inparticular, all semiconductor lasers and all optical elements areconnected simultaneously in a common method step.

According to at least one embodiment of the method of manufacturing alaser diode, the optical elements and the semiconductor lasers aresingulated in a method step D, wherein exactly one optical element beingassigned to each semiconductor laser after singulation. For example, theoptical elements and the semiconductor lasers are singulated in a commonprocess step. For example, the optical elements and the semiconductorlasers are singulated by sawing, a laser cutting process or an etchingprocess.

Advantageously, such a method allows a simultaneous arrangement of aplurality of optical elements on a plurality of semiconductor lasers,whereby both the optical elements and the semiconductor lasers can bemanufactured in a common process.

According to at least one embodiment of the method of manufacturing alaser diode, method step D is carried out after method step C. Inparticular, the optical elements and the semiconductor lasers aresingulated after the optical elements have been cohesively connected tothe semiconductor lasers. In particular, method steps A, B, C and D arecarried out in this sequence. Advantageously, such a procedure makes itpossible to simplify the alignment of the optical element 20 relative tothe semiconductor laser 10. Furthermore, this enables a particularlytime-saving production of a plurality of light-emitting diodes.

According to at least one embodiment of the method of manufacturing alaser diode, a laser diode described here is manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantageous embodiments and developments of the laser diode and themethod of manufacturing a laser diode will become apparent from theexemplary embodiments described below in association with the figures:

FIGS. 1, 2, 3 and 5D show different exemplary embodiments of a laserdiode;

FIGS. 4, 5A, 5B, 5C and 5D show different methods steps of the method ofmanufacturing a laser diode;

FIGS. 6, 7, 8 and 9 show further exemplary embodiments of a laser diodeor a method of manufacturing a laser diode; and

FIGS. 10A, 10B, 10C, 11A and 11B show further exemplary embodiments of alaser diode or a method of manufacturing a laser diode.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the exemplary embodiments and figures, similar and similarly actingconstituent parts are provided with the same reference symbols. Theelements illustrated in the figures and their size relationship amongone another should not be regarded as true to scale. Rather, individualelements may be represented with an exaggerated size for the sake ofbetter representability and/or for the sake of better understanding.

FIG. 1 shows a schematic sectional view of a laser diode 1 describedhere according to a first exemplary embodiment. The laser diodecomprises a surface-emitting semiconductor laser 10, which is configuredto emit electromagnetic radiation E. In particular, the semiconductorlaser 10 is configured to emit electromagnetic radiation E perpendicularto its main extension plane. In particular, the semiconductor laser 10is a VCSEL. For example, the semiconductor laser 10 is formed with alayer stack comprising several semiconductor layers. During normaloperation, the semiconductor laser emits electromagnetic radiation Efrom the semiconductor layers in a radiation direction L that isparallel to the stacking direction, for example.

Further, the laser diode 1 comprises a carrier 30 arranged on a majorsurface of the semiconductor laser 10. For example, the carrier 30 is asubstrate on which the semiconductor laser 10 is manufactured. Inparticular, the semiconductor laser 10 is manufactured by means of anepitaxial process on the carrier 30. An optical element 20 is arrangedon one side of the semiconductor laser 10 facing away from the carrier30. The optical element 20 is arranged downstream of the semiconductorlaser 10 in the radiation direction L. The optical element 20 comprisesa diffractive structure 200 or a meta-optical structure 200 or a lensstructure 200 which is configured to influence electromagnetic radiationE emitted by the semiconductor laser 10. For example, the diffractivestructure 200 comprises elements 205 arranged periodically along themain plane of extension of the optical element 20, which in at least onespatial direction transverse to the emission direction L have amagnitude in the order of the wavelength range of the emittedelectromagnetic radiation E. For example, the optical elements 205 areformed as recesses in a first layer 201 of the optical element 20. Inparticular, the recesses with which the elements 205 are formed may befilled with a gaseous material. The elements 205, which are shownschematically in FIG. 2 , form substructures of the diffractivestructure 200 or the meta-optical structure 200 or the lens structure200.

The semiconductor laser 10 and the optical element 20 are mechanicallyfixed to each other by means of a connection means 50. For example, theconnection means 50 is an adhesive, in particular an epoxy resin or asilicone. The connection means 50 is arranged on a radiation exitsurface 10 a of the laser diode 10. The connection means 50 forms inparticular a connecting layer 50. The connecting layer 50 is arranged ina vertical direction, for example, between the optical element 20 andthe semiconductor laser 10. For example, a region between the opticalelement 20 and the semiconductor laser 10 is filled with non-gaseousmaterial. In particular, the connection means 50 completely covers theradiation exit surface 10 a. The optical element 20, in particular thefirst layer 201, is formed, for example, with a material having the samerefractive index as the connection means 50.

A first contact surface 41 and a second contact surface 42 are arrangedon the carrier 30. By means of the first contact surface 41 and thesecond contact surface 42, the laser diode 1 can be electricallycontacted and operated. The first contact surface 41 is located on aside of the carrier 30 facing away from the semiconductor laser 10. Forexample, the side of the carrier 30 facing away from the semiconductorlaser 10 is completely covered by the first contact surface 41. Thelaser diode 1 can be mounted with the first contact surface 41 on anelectrically conductive surface, which can also serve as a heat sink forthe laser diode 1. The second contact surface 42 is arranged on one sideof the carrier 30, facing away from the first contact surface 41,laterally next to the semiconductor laser 10. For example, the secondcontact surface 42 can be electrically contacted by means of a bondingwire 43.

FIG. 2 shows a schematic sectional view of a laser diode 1 describedhere according to another exemplary embodiment. In contrast to theexemplary embodiment shown in FIG. 1 , the semiconductor laser 10 is notarranged on a carrier 30. In particular, the semiconductor laser 10comprises electrical contact surfaces 4 exclusively on a side facingaway from the optical element 20. The semiconductor laser 10 and theoptical element 20 are cohesively connected to each other by aconnection means 50. For example, the optical element 20 is formed witha material which has the same refractive index as the connection means50. In particular, the electromagnetic radiation E emitted by thesemiconductor laser 10 is not refracted at the interface between theconnection means 50 and the optical element 20.

The optical element 20 terminates flush with the semiconductor laser 10in lateral directions R which are perpendicular to the radiationdirection L of the semiconductor laser 10. In particular, the opticalelement 20 does not project beyond the semiconductor laser 10 in lateraldirections R. The optical element 20 is formed by a first layer 201 anda second layer 202. The second layer 202 is not contiguous and isarranged in recesses of the first layer 201. For example, the secondlayer 202 is completely surrounded on all sides by the first layer 201.The first 201 and the second 202 layer form elements 205 which act as adiffractive structure 200 for the electromagnetic radiation E emitted bythe semiconductor laser 10.

It is possible that the elements 205 are formed by substructures of themeta-optical structure 200 or the lens structure 200. The substructuresof the meta-optic structure 200 or the lens structure 200 can becompletely surrounded on all sides by the first layer 201. Especially inthis sense the diffractive structure 200 or the meta-optic structure 200or the lens structure 200 is embedded in the optical element 20,especially in the first layer 201. The first layer 201 serves inparticular as a planarization layer and/or as an encapsulation layer ofthe optical element 20. Deviating from FIG. 2 , it is possible thatseveral or all elements 205, which are formed in particular bysubstructures of the meta-optical structure 200 or the lens structure200, are formed contiguously. For example, the elements 205 form a lensrow, a lens matrix from several lens rows of the lens structure 200 or ameta lens, in particular from nanosubstructures of the meta-opticstructure 200.

The diffractive structure 200, the meta-optical structure 200 or thelens structure 200 is arranged at a distance from the side 10 a of thesemiconductor laser 10 facing the optical element. In particular, thedistance D between the diffractive structure 200, the meta-opticalstructure 200 or the lens structure 200 and the radiation exit surface10 a can be adapted via the thickness of the connection means 50 and/orthe thickness of the optical element 20, in particular the first layer201.

If the optical element 20 comprises a lens structure 200, the element205 can be formed as a lens. In particular, element 205 forms an opticalsubstructure of the lens structure 200. The majority of elements 205 mayform one or more rows of lenses. The elements 205 can be embedded in thefirst layer 201. The elements 205 may have a higher or lower refractiveindex than a material of the first layer 201. For example the refractiveindices of the elements 205 and the material of the first layer 201differ by at least 0.1, 0.2, 0.5 or by at least 0.5, for example between0.1 and 1 inclusive or between 0.1 and 2 inclusive. The first layer 201may be formed as a planarization layer or as an encapsulation layer ofthe diffractive structure 200, the meta-optical structure 200, the lensstructure 200 or the optical element 20.

Furthermore, an anti-reflection layer 8 is arranged on a surface of theoptical element 20 facing away from the semiconductor laser 10. Inparticular, the anti-reflection layer 8 is arranged exclusively on anoutwardly exposed surface 1 a of the optical element 20.

FIG. 3 shows a schematic sectional view of a laser diode 1 describedhere according to another exemplary embodiment. In this exemplaryembodiment, the optical element 20 and the semiconductor laser 10 arecohesively connected to each other by means of the connection means 50.Furthermore, the connection means 50 surrounds the semiconductor laser10 and the optical element 20 in lateral directions R. In particular,all surfaces of the optical element 20 and the semiconductor laser 10which run transversely to the radiation direction L of the semiconductorlaser 10 are completely covered by the connection means 50. Inparticular, the connection means 50 also completely covers the surfaceof the optical element 20 facing away from the semiconductor laser 10.For example, the connection means 50 is a capsulation means which istransparent to the electromagnetic radiation E emitted by thesemiconductor laser 10.

The semiconductor laser 10 is cohesively connected to a housing 60 on aside facing away from the optical element 20 by means of the secondcontact surface 42. For example, the housing 60 is at least partiallyelectrically conductive and serves as a heat sink and for electricalcontacting of the semiconductor laser 10. The first contact surface 41is arranged on the radiation exit surface 10 a of the semiconductorlaser 10. The first contact surface 41 is electrically conductivelyconnected to the housing 60 by means of a bonding wire 43. Inparticular, the bonding wire 43 and the second contact surface 42 arenot electrically conductively connected to each other via the housing60. The first electrical contact surface 41 is arranged on the radiationexit surface 10 a of the semiconductor laser 10 facing the opticalelement 20. The optical element 20 does not completely cover theradiation exit surface 10 a of the semiconductor laser 10. Inparticular, the first contact surface 41 is not covered by the opticalelement 20.

The optical element 20 is formed by a first layer 201 and a second layer202. The first layer 201 has a plurality of recesses which arecompletely filled with the material of the second layer 202. The first201 and the second 202 differ in at least one optical property, such astheir refractive index, their reflectivity and/or their absorption forelectromagnetic radiation E emitted by the semiconductor laser 10. Thefirst 201 and the second 202 form a diffractive structure 200 comprisinga plurality of elements 205 configured to influence electromagneticradiation E emitted by the semiconductor laser 10.

According to FIG. 3 , the semiconductor laser 10 projects beyond theoptical element 20 in a lateral direction. The semiconductor laser 10can be partially free of a covering by the optical element 20 so that itcan be electrically contacted, in particular on its side facing theoptical element 20. In plan view, the optical element 20 covers thesemiconductor laser 10 only partially. For example, the semiconductorlaser 10 has a surface facing the optical element 20 with a free regionwhich is free of a covering by the optical element 20. One or morecontact surfaces 41 and/or 42 may be formed on the free region.

Deviating from FIG. 3 , it is possible that the optical element 20 shownin FIG. 3 is constructed analogously to the optical element 20 shown inFIG. 2 . Deviating from FIG. 3 , it is also possible that both the firstcontact surface 41 and the second contact surface 42 are arrangedanalogously to the exemplary embodiment of a laser diode 1 shown in FIG.2 on a rear side of the semiconductor laser 10 facing away from theoptical element 20. The semiconductor laser 10 is configured inparticular as a surface-mountable component and can only be electricallycontacted externally via its rear side. The first contact surface 41 andthe second contact surface 42 are particularly assigned to differentelectrical polarities of the semiconductor laser 10 and the laser diode1, respectively. For example, the semiconductor laser 10 has the form ofa flip chip.

FIG. 4 shows part of a method of manufacturing a plurality of laserdiodes 1. In this method step, the semiconductor lasers 10 arecohesively connected to a housing 60 with their second contact surface42. The semiconductor lasers 10 are electrically conductively connectedto the housing 60 by means of a bonding wire 43 at their first contactsurface 41. The connection means 50, which serves as a capsulationmeans, is arranged in the housing 60.

The connection means 50 is arranged at least on the radiation exitsurface 10 a of the semiconductor laser 10. In addition, the connectionmeans 50 is arranged in the housing 60 such that side surfaces of thesemiconductor laser 10, which connect the side of the semiconductorlaser 10 facing away from the optical element 20 and the side of thesemiconductor laser 10 facing away from the optical element 10 a, arecovered. The connection means 50, for example, can be arranged in amethod step in the housing 60 such that all radiation exit surface 10 aof the semiconductor laser 10 are covered with a predetermined thicknessof the connection means 50. In a further method step, optical elements20 can be arranged on the semiconductor lasers 10, so that the opticalelements 20 are arranged downstream of the semiconductor lasers 10 in aradiation direction L. In a subsequent method step, additionalconnection means 50 is arranged in the housing 60 so that the opticalelements 20 are completely covered by the connection means 50. In asubsequent method step, the laser diodes 1 are singulated along theseparation lines 7. For example, the laser diodes 1 are singulated alongthe separation lines 7 by means of a sawing or laser cutting process.

FIG. 5A shows a method described here for the manufacturing of a laserdiode 1 after method steps A and B. In method step A, a plurality ofsurface emitting semiconductor lasers 10 were provided in a firstcomposite 110. For example, the semiconductor lasers 10 are arranged ona common carrier 30. In particular, the semiconductor lasers 10 on thecommon carrier 30 are manufactured in a common manufacturing process.Contact surfaces 4 are arranged on a side of the carrier 30 facing awayfrom the semiconductor lasers 10.

Furthermore, in a method step B, a plurality of optical elements 20 withdiffractive structures 200, meta-optical structures 200 or with lensstructures 200 are provided in a second composite 120. The plurality ofoptical elements 20 is cohesively connected to each other. Inparticular, the optical elements 20 are manufactured in a commonprocess. The diffractive structures 200, the meta-optical structures 200or the lens structures 200 are formed with elements 205 which arearranged, for example, on a surface of a first layer 201 of the opticalelement 20 facing away from the laser diode 10. Alternatively, thediffractive structures 200, the meta-optical structures 200 or the lensstructures 200 can be completely surrounded by the material of the firstlayer 201 of the optical element 20. For example, the diffractivestructures 200 or the lens structures 200 can be formed by varying thethickness of the optical element 20.

FIG. 5B shows a schematic sectional view of a method described here forthe manufacturing of a laser diode after method step C. In method stepC, the plurality of optical elements in a composite and the plurality ofsemiconductor lasers in a composite were cohesively connected to eachother. For example, the first composite 110 and the second composite 120were cohesively connected to each other via bonding. Alternatively, thefirst bond 110 and the second bond 120 can be cohesively connected toeach other by means of a connection means 50.

FIG. 5C shows a method step D of a method described here formanufacturing a laser diode 1. In a method step D, the first composite110 and the second composite 120 are singulated. The optical elements 20and the semiconductor lasers 10 are cut perpendicular to their mainextension plane along the separation line 7. For example, the firstcomposite 110 and the second composite 120 are cut using a laser cuttingprocess, a sawing process or an etching process. After singulation, eachsemiconductor laser 10 is assigned exactly one optical element 20.

FIG. 5D shows the laser diodes 1 after carrying out method steps A to Daccording to the method described here for manufacturing a laser diode1. In particular, the laser diode 1 described here has electricalcontact surfaces 4 exclusively on one side facing away from the opticalelement 20. The semiconductor lasers 10, the contact surfaces 4, thecarriers 30 and the optical elements 20 are cut in a common method step.The optical elements 20, the semiconductor lasers 10 and the carriers 30terminate flush with each other in lateral directions.

The exemplary embodiment shown in FIG. 6 of a laser diode 1 correspondsessentially to the exemplary embodiment shown in FIG. 3 . In contrast tothis, the connection means 50 is arranged exclusively between thesemiconductor laser 10 and the optical element 20. The semiconductorlaser 10 and the optical element 20 are completely enclosed in thelateral direction by a cladding 90. For example, the side surfaces ofthe semiconductor laser 10 and/or the connection means 50 are completelycovered by a material of the cladding 90. According to FIG. 6 , the sidesurfaces of the optical element 10 are only partially covered by thecladding material 90, in particular substantially up to the verticalheight of the elements 205. However, it is possible that the side facesof the optical element 10 are completely covered by the claddingmaterial 90. In plan view of the optical element, the semiconductorlaser 10 or the optical element 10 is preferably free of a covering bythe cladding 90.

For the electromagnetic radiation emitted by the semiconductor laser 10,the material of the cladding 90 may be chosen to be not transmissive.For example, the cladding material 90 acts radiation-absorbing orradiation-reflecting. In particular, the cladding is not transmissivefor electromagnetic waves with a peak wavelength of the light emitted bythe semiconductor laser 10. By covering the side surfaces of thesemiconductor chip 10 and/or the optical element 20, it can be preventedthat the electromagnetic radiation emitted by the semiconductor laser 10is emitted laterally from the semiconductor laser 10 or from the opticalelement 20, before it hits the diffractive structures 200, themeta-optical structures 200 or the lens structures 200.

A layer, such as the cladding 90 or the cover layer 91, is transmissivefor radiation if preferably at least 50%, 60%, 70%, 80% or at least 90%of the radiation emitted by the semiconductor laser can be transmittedthrough this layer. On the other hand, a layer is not transmissive if ittransmits not more than 50%, 40%, 30%, 20%, 10% or not more than 5% ofthe radiation emitted by the semiconductor laser.

According to FIG. 6 , the laser diode 1 comprises a cover layer 91. Inparticular, the cover layer 91 directly adjoins the cladding 90 and/or asurface of the optical element 20 facing away from the semiconductorlaser 10 or the anti-reflection layer 8. In plan view, the cover layer91 can cover the optical element 20, the semiconductor laser 10 and/orthe cladding 90, in particular completely. For the electromagneticradiation emitted by the semiconductor laser 10, the material of thecladding 91 may be transmissive. It is possible that the cover layer 91is not transmissive to visible light and transmissive to electromagneticradiation in the infrared range, or vice versa.

In FIG. 6 , the housing 60 comprises a cavity in which the cover layer91, the cladding 90, the optical element 20 and/or the semiconductorlaser 10 is/are arranged. Deviating from FIG. 6 , it is possible thatthe housing 60 comprises only a laterally extending region and novertically extending regions. In this case, the housing 60 does not havea cavity with inner walls from the vertically extending regions, butonly a laterally extending region on which the semiconductor laser 10 isarranged. In particular, the laterally extending region is in the formof a carrier, in particular in the form of a printed circuit board, towhich the semiconductor laser is electrically conductively connected.Such a laser diode 1 is shown, for example, in FIG. 7 . Such a laserdiode 1 comprises outer side surfaces which are formed by surfaces ofthe cladding 90 and/or the cover layer 91. In particular, laser diode 1is formed as a chip-scale package (CSP) whose lateral and/or verticalexpansion is approximately in the same order of magnitude as the lateraland/or vertical expansion of the semiconductor laser 10.

The exemplary embodiment shown in FIG. 7 for a part of a method ofmanufacturing a plurality of laser diodes 1 essentially corresponds tothe exemplary embodiment shown in FIG. 4 . In contrast to this, thecladding body or the cladding 90 is made of a material different from amaterial of the connection means 5, analogous to the exemplaryembodiment shown in FIG. 6 . For example, the cladding is molded orformed by filling a cavity in which the semiconductor laser 10 or aplurality of semiconductor lasers 10 are arranged. The arrangement ofthe claddings 90 and/or the cover layer 91 in FIGS. 6 and 7 may beidentical. In contrast to FIGS. 6 and 7 , the optical element 10 maytake other forms described here.

The exemplary embodiment shown in FIG. 8 for a laser diode 1 isessentially the same as the exemplary embodiment shown in FIG. 6 for alaser diode 1. In contrast to this, the semiconductor laser 10 comprisesa first contact surface 41 and a second contact surface 42 on a rearside of the semiconductor laser 10 facing away from the optical element20. The semiconductor laser 10 can therefore only be electricallycontacted externally via its rear side.

The exemplary embodiment shown in FIG. 9 for a method step ofmanufacturing a plurality of laser diodes 1 essentially corresponds tothe exemplary embodiment shown in FIG. 7 . In contrast to this, thesemiconductor laser 10 or the semiconductor lasers 10 can beelectrically contacted externally, analogous to FIG. 8 , exclusively viaits rear side(s).

The exemplary embodiment shown in FIG. 10A for a laser diode 1corresponds essentially to the exemplary embodiment shown in FIG. 6 fora laser diode 1. In contrast to this, the laser diode 1 comprises a mask25. The mask 25 is arranged in vertical direction between the opticalelement 20 and the semiconductor laser 10. In FIG. 10A, the mask 25 isarranged between the optical element 20 and the connection means 50. Inparticular, mask 25 is located on the back of optical element 20, i.e.,on a surface of optical element 20 facing the semiconductor laser 10. Itis possible that mask 25 is applied directly to the optical element 20.The mask 25 can be applied to the optical element by means of a coatingor a deposition method, for example by vapor deposition or sputtering.

In particular, the mask 25 is a shadow mask. The mask 25 may comprisepatterns which, in particular, form a predefined pictogram. The mask 25is preferably a mask 25 that forms a pictogram. The mask 25 may compriseregions transmissive for radiation that define the shape of thepictogram to be displayed. Regions that are not transmissive forradiation may be formed by a radiation-absorbing and/or aradiation-reflecting material. For example, the regions not transmissivefor radiation of the mask 25 may be formed by a metal or metal alloy.

The mask 25 may comprise regions transmissive for radiation that allowthe radiation emitted by the semiconductor laser 10 to pass the mask 25unhindered or essentially unhindered. The regions transmissive forradiation may be openings or free regions of the mask 25. It is alsopossible that the regions transmissive for radiation of the mask 25 areformed by a material transmissive for radiation. Due to the regionstransmissive for radiation and the regions not transmissive forradiation, the mask can form an arbitrary pattern and thus an arbitrarypictogram. During operation, the particularly compact laser diode 1 withthe semiconductor laser 10, the mask 25 and the optical element 20 canproject a pictogram onto a target surface without any additional aids.

The exemplary embodiment shown in FIG. 10B for a laser diode 1corresponds essentially to the exemplary embodiment shown in FIG. 8 fora laser diode 1. In contrast to this, the laser diode 1 comprises a mask25 analogous to the exemplary embodiment shown in FIG. 10A. In contrastto the exemplary embodiment shown in FIG. 10A, the laser diode 1comprises a spacer 51 as shown in FIG. 10B. The spacer 51 is arrangedalong a vertical direction between the semiconductor laser 10 and themask 25. The spacer 51 is preferably transmissive for radiation. Forexample, the spacer 51 is formed of glass, quartz glass or a glass-likematerial. The spacer 25 can be used to adjust an ideal distance betweenthe semiconductor laser 10 and the mask 25, so that the mask 25 isoptimally, approximately homogeneously, illuminated. According to FIG.10B, the spacer 25 is arranged between two connecting layers 50 and, inparticular, adjoins directly to these connecting layers 50. Thesemiconductor laser 10 and the mask 25 can each be directly adjacent toone of the two connection layers 50.

The exemplary embodiment shown in FIG. 10C for a laser diode 1 isessentially the same as the exemplary embodiment shown in FIG. 10B for alaser diode 1. In contrast, the mask 25 is not arranged on the back ofthe optical element 20 but on a surface of the spacer 51. In this sensethe mask 25 is not part of the optical element 20 but part of the spacer51. While the mask 25 is arranged according to FIG. 10B on the opticalelement 20 and only mechanically connected to the spacer 51 via theconnecting layer 50, the mask 25 according to FIG. 10C is arranged onthe spacer 51 and only mechanically connected to the optical element 20via the connecting layer 50.

The mask 25 is arranged in particular on a surface of the spacer 51facing away from the semiconductor laser 10. It is possible that themask 25 is applied directly to the spacer 51. The mask 25 can be appliedto the spacer 51 by means of a coating or a deposition process, forexample by vapor deposition or sputtering.

The exemplary embodiments shown in FIGS. 11A and 11B for a part of amethod of manufacturing a plurality of laser diodes 1 essentiallycorrespond to the exemplary embodiments shown in FIGS. 7 and 9 .

In contrast, the laser diodes 1 each comprise a mask 25, a spacer 51and, in particular, an anti-reflection layer 8. The laser diode 1described in connection with FIGS. 1 to 9 may also comprise such a mask25 and/or such a spacer 51, wherein the mask 25 and the spacer 51 aredescribed in more detail in particular in connection with FIGS. 10A to10C. According to FIGS. 11A and 11B, the cladding 90 completely coversthe side surfaces of the semiconductor laser 10, the mask 25 and/or thespacer 51 as well as the connection layer 50 or the connection layers50. The antireflection layer 8 is free of a covering by the cladding 90.Apart from one side facing the optical element 20, the antireflectionlayer 8 in particular is completely covered by the cover layer 91.

Deviating from the FIGS. 8, 9, 10B, 10C and 11B, it is possible that thefinished laser diode 1 is free of a housing 60, as shown in thesefigures. For example, the housing 60 can be completely removed from thelaser diode 1 or from the laser diodes 1. Such a laser diode 1 has arear side, which is formed in particular by the rear side of thesemiconductor laser 10 and/or by the rear surface of the cladding 90. Inparticular, the contact surfaces 41 and 42 on the rear side of the laserdiode 1 are freely accessible. In particular, such a laser diode 1 isformed as a surface-mountable component. A vertical overall height ofthe laser diode 1 is given in particular exclusively by the sum of thevertical heights of the cladding 90 and the cover layer 91. Amechanically stable and flat CSP component (Chip-scale package) with aparticularly low overall height can thus be achieved.

The patent application claims the priority of German patent applicationDE 10 2017 112 235.4, the disclosure content of which is herebyincorporated by reference.

The invention is not restricted to the exemplary embodiments by thedescription on the basis of said exemplary embodiments. Rather, theinvention encompasses any new feature and also any combination offeatures, which in particular comprises any combination of features inthe patent claims and any combination of features on the exemplaryembodiments, even if this feature or this combination itself is notexplicitly specified in the patent claims or exemplary embodiments.

The invention claimed is:
 1. A laser diode comprising: a surfaceemitting semiconductor laser configured to emit electromagneticradiation; and an optical element arranged downstream of thesemiconductor laser in a radiation direction, wherein the opticalelement comprises a diffractive structure or a meta-optical structure ora lens structure, wherein the optical element and the semiconductorlaser are cohesively connected to each other, wherein the semiconductorlaser and the optical element are integrated with the laser diode,wherein the semiconductor laser and the optical element are laterallyenclosed by a cladding, wherein the semiconductor laser and the opticalelement remain uncovered from the cladding in plan view, and wherein thecladding is configured to reflect or absorb the electromagneticradiation.
 2. The laser diode according to claim 1, wherein the opticalelement is in direct contact with a radiation exit surface of thesemiconductor laser facing the optical element.
 3. The laser diodeaccording to claim 1, wherein the optical element and the semiconductorlaser are cohesively connected by a connector.
 4. The laser diodeaccording to claim 3, wherein the optical element is formed with amaterial having the same refractive index as the connector.
 5. The laserdiode according to claim 1, wherein the optical element and thesemiconductor laser are cohesively connected by a connector, and whereinthe connector surrounds the semiconductor laser and the optical elementin lateral directions.
 6. The laser diode according to claim 1, whereina region between the optical element and the semiconductor laser isfilled with non-gaseous material.
 7. The laser diode according to claim1, wherein the optical element does not completely cover a radiationexit surface of the semiconductor laser facing the optical element. 8.The laser diode according to claim 1, wherein the optical elementterminates flush with the semiconductor laser in lateral directions. 9.The laser diode according to claim 1, wherein the diffractive structureor the meta-optical structure or the lens structure is arranged at adistance from a radiation exit surface of the semiconductor laser facingthe optical element.
 10. The laser diode according to claim 1, furthercomprising an anti-reflection layer exclusively arranged on an outwardlyexposed surface of the optical element.
 11. The laser diode according toclaim 1, further comprising an electrical contact surface on a surfaceof the semiconductor laser facing the optical element, wherein thecontact surface is not covered by the optical element.
 12. The laserdiode according to claim 1, wherein the semiconductor laser compriseselectrical contact surfaces exclusively on a side facing away from theoptical element.
 13. The laser diode according to claim 1, furthercomprising: a mask, wherein the mask is formed in a vertical directionbetween the optical element and the semiconductor laser, and wherein themask is configured to generate a pictogram.
 14. The laser diodeaccording to claim 13, further comprising: a spacer, wherein the spaceris arranged in the vertical direction between the optical element andthe semiconductor laser, wherein the spacer is transparent for theelectromagnetic radiation, wherein the spacer sets a predetermineddistance between the mask and the semiconductor laser, and wherein thesemiconductor laser, the spacer and the optical element are cohesivelyconnected to each other.
 15. The laser diode according to claim 1,wherein the cladding comprises a material which is radiation-absorbingat least for visible light or for light in an infrared spectral range,wherein the cladding completely laterally encloses the semiconductorlaser and the optical element, and wherein the cladding partially coversside surfaces of the optical element such that the side surfaces of theoptical element remain uncovered by the cladding at least from avertical height or at least from an upper edge of the diffractivestructure, the meta-optical structure or the lens structure.
 16. Thelaser diode according to claim 1, wherein the cladding completely coversside surfaces of the semiconductor laser, wherein the cladding at leastpartially covers side surfaces of the optical element, wherein thesemiconductor laser and the optical element are covered in plan view bya cover layer transmissive for the electromagnetic radiation, andwherein the cover layer adjoins the cladding.
 17. The laser diodeaccording to claim 16, wherein the cladding comprises a material nottransmissive for the electromagnetic radiation and the cladding isconfigured to be not transmissive for light in an infrared spectralrange, and wherein a material and a layer thickness of the cover layerare selected such that the cover layer is not transmissive for light ina visible spectral range and transmissive for the light in the infraredspectral range.
 18. A laser diode comprising: a surface emittingsemiconductor laser configured to emit electromagnetic radiation; and anoptical element arranged downstream of the semiconductor laser in aradiation direction, wherein the optical element comprises a diffractivestructure or a meta-optical structure or a lens structure, wherein theoptical element and the semiconductor laser are cohesively connected toeach other, wherein the semiconductor laser and the optical element areintegrated with the laser diode, wherein a peak wavelength of theelectromagnetic radiation is a wavelength in an infrared spectral range,wherein the semiconductor laser and the optical element are laterallyenclosed by a cladding, wherein the semiconductor laser and the opticalelement remain uncovered from the cladding in plan view, and wherein thecladding is configured to reflect or absorb the electromagneticradiation.
 19. The laser diode according to claim 18 wherein the opticalelement and the semiconductor laser are cohesively connected by aconnector, wherein the connector surrounds the semiconductor laser andthe optical element in lateral directions, wherein the semiconductorlaser and the optical element are covered in plan view by a cover layertransmissive for the electromagnetic radiation, and wherein a materialand a layer thickness of the cover layer are selected such that thecover layer is not transmissive for light in a visible spectral rangeand transmissive for light in the infrared spectral range.